Adaptive<i>d</i>-Axis Current Control of RSyM for Photovoltaic Water Pumping Incorporating Cross Saturation
Anshul Varshney, Utkarsh Sharma, Bhim Singh
Abstract
In this article, an adaptive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current control of a reluctance synchronous motor (RSyM) drive for a photovoltaic (PV) water pumping system has been presented, which incorporates impacts of the cross saturation in realtime to compensate the errors in the speed estimation. The response of the RSyM drive is optimized by adaptive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current estimation. A real-time assessment of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis inductance is carried out to include the cross magnetization into consideration for improving the efficiency of the motor. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current is varied for minimum value to provide the maximum output torque. Here, a two-stage solar energy conversion system is used to drive the centrifugal pump coupled to an RSyM drive. A boost converter is used to optimize the PV power using an incremental conductance based maximum power point tracking technique. The boost converter supplies power to a dc–ac, an insulated gate bipolar transistor based inverter through a capacitor connected across the dc link. The control of RSyM is implemented using the adaptive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i<sub>d</sub></i> -based vector control algorithm. An adaptive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current is fed to the controller corresponding to the available solar irradiation, which aids in the maximization of drive efficiency and the minimization of stator copper losses. Moreover, this control improves the motor input terminal power factor. A speed/position sensorless control technique is utilized to reduce the complexity and to enhance the reliability of a water pumping system. The suitability of an implemented controller is verified through the experimental results taken on a 3.7 kW RSyM-driven PV energized water pumping system.